Generally, in a large vehicle, such as a truck or bus, a pneumatic brake device using compressed air as a working fluid for actuating brake chambers is adopted. This type of brake device has a configuration where compressed air discharged from an air compressor is stored in an air tank and the compressed air in the air tank is supplied as necessary to each brake chamber. An air dryer for adsorbing moisture from the compressed air to perform a drying process is located between the air compressor and the air tank.
Conventionally, as this type of air dryer, a configuration has been proposed that includes a supporting base including an inlet receiving compressed air to be subject to the drying process and an outlet delivering processed compressed air that has undergone the drying process, a drying agent container, which is supported on the supporting base, contains a drying agent in the interior, and enables the drying process to be performed by passing the compressed air from the inlet through the drying agent, and an outer cover, which surrounds the outer side of the drying agent container on the supporting base and defines a chamber storing the compressed air between itself and the drying agent container (see, for example, Patent Document 1).
For example, an air dryer has been known that removes moisture and oil in compressed air delivered from an air compressor in a brake device for large automobile. This air dryer includes, in addition to an air intake inlet for taking in the compressed air (compressed air before removal of moisture and oil) from the air compressor and a processed air delivery outlet for delivering dried air that has undergone the moisture and oil removal process, a drain valve for discharging drain, containing the removed moisture, oil, and the like, together with air (see, for example, Patent Documents 1 and 3). In the present description, this drain valve will be referred to as an “exhaust valve” from the standpoint of discharging air.
With this exhaust valve, a loud air discharge noise (explosive noise) is generated when the valve is opened and therefore to reduce this noise, a silencer, such as described in Patent Document 2, is connected to the exhaust valve in some cases.
Conventionally, as described in Patent Document 4, a drying device (air dryer) has been known that is used in an air brake device of a vehicle to remove moisture in compressed air. The drying device includes a drying container filled with a regenerable drying agent and a regeneration tank storing dry compressed air from which moisture has been adsorbed by the drying agent. The device is configured such that the compressed air delivered from an air compressing device is dried by the drying agent in the drying container and stored in an air tank of the air brake device. In this process, some of the dry compressed air is stored in the regeneration tank inside the drying device. It is configured that the dry compressed air in the regeneration tank flows in reverse to enable regeneration of the drying agent inside the drying container.
Also conventionally, in a large vehicle, such as a truck or bus, a pneumatic type brake device or suspension device using compressed air as the working fluid is adopted, and a compressed air supply device for a vehicle that supplies compressed air to these respective devices is installed. The compressed air supply device for a vehicle includes an air compressor discharging the compressed air, an air dryer removing moisture and other foreign matter from the compressed air discharged from the air compressor, and an air tank storing the compressed air passed through the air dryer and supplies the compressed air in the air tank as necessary to the brake device and the suspension device.
As this type of compressed air supply device for a vehicle, a device is known one that includes a pressure governor located in an unloading pipe between the air compressor and the air tank. The pressure governor switches the operation of the air compressor to loading or unloading so that an air pressure inside the air tank is within a predetermined range. When the air compressor is unloaded, opens an exhaust valve of the air dryer to regenerate the drying agent inside the air dryer (see, for example, Patent Document 5).
Further conventionally, as described in Patent Document 4, the drying device (air dryer) has been known that is used in an air brake device of a vehicle to remove moisture in compressed air. The drying device includes the drying container filled with the regenerable drying agent and the regeneration tank storing the dry compressed air from which moisture has been adsorbed by the drying agent. The device is configured such that the compressed air delivered from the air compressing device is dried by the drying agent in the drying container and stored in the air tank of the air brake device. In this process, some of the dry compressed air is stored in the regeneration tank inside the drying device. It is configured that the dry compressed air in the regeneration tank flows in reverse to enable regeneration of the drying agent inside the drying container.